DOCSLIB.ORG

Generation and Use of New Tools for the Characterisation of Gut Hormone Receptors

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Generation and Use of New Tools for the Characterisation of Gut Hormone Receptors Generation and use of new tools for the characterisation of gut hormone receptors Emma Kate Biggs August 2018 Selwyn College, University of Cambridge This dissertation is submitted for the degree of Doctor of Philosophy Emma Kate Biggs Generation and use of new tools for the characterisation of gut hormone receptors Abstract Enteroendocrine hormones released from the intestine following food intake have several roles in the control of metabolism, some of which are exploited therapeutically for the treatment of type 2 diabetes. Within this thesis, focus has been on the receptors of the gut hormones glucagon-like peptide-1 (GLP-1), glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-2 (GLP-2). In recent years there has been a surge of interest in the enteroendocrine hormones particularly due to the success of GLP-1 mimetics in the treatment of type 2 diabetes. GLP-1 is an incretin hormone, which enhances glucose induced insulin secretion by binding GLP-1 receptors (GLP1R) on pancreatic β-cells. Despite the therapeutic success, several extra-pancreatic clinical effects of GLP-1 remain unexplained. Here, a GLP1R monoclonal antagonistic antibody that can block GLP1R signalling in vivo has been developed and characterised, providing a new tool for the study of GLP1R physiology. GIP is the second incretin hormone, initially referred to as the ‘ugly duckling’ incretin hormone due to it’s ineffectiveness in inducing insulin secretion in type 2 diabetic patients. Aside from the incretin actions, GIP is thought to be involved in the regulation of high-fat diet (HFD) induced obesity. A new transgenic mouse model expressing a fluorescent reporter under the control of the Gipr promoter has been used here to identify GIPR expressing cells. This model showed GIPR expression in the pancreas, adipose tissue, duodenum and nodose ganglia. Surprisingly GIPR expressing cells were found centrally, in areas of the hypothalamus involved in the regulation of food intake and energy expenditure. We consequently sought to investigate the function of GIPR expressing hypothalamic cells. GLP-2, unlike GLP-1 and GIP, is not an incretin hormone. Rather, GLP-2 has been implicated in the regulation of epithelial cell proliferation and apoptosis within the intestine. Therapeutically, an analogue of GLP-2 is used for the treatment of short bowel syndrome. A common missense mutation in the GLP-2 receptor (GLP2R), D470N, has been found to be associated with type 2 diabetes, and here we sought to understand the mechanism underlying this association. The D470N mutant has decreased β-arrestin recruitment, though the significance of this finding will need further research. Overall; the new monoclonal antagonistic GLP1R antibody will help to further understand GLP1R physiology, the new transgenic GIPR mouse model has contributed to the understanding of GIPR localisation, and cell based assays have identified functional implications of a polymorphism in the GLP2R associated with an increased risk of diabetes. It is hoped that further understanding of the physiology of these gut hormone receptors will be critical in the development of new therapeutics for diabetes and obesity. Declaration This dissertation is the result of my own work and includes nothing which is the outcome of work done in collaboration except as declared in the Preface and specified in the text. It is not substantially the same as any that I have submitted, or, is being concurrently submitted for a degree or diploma or other qualification at the University of Cambridge or any other University or similar institution except as declared in the Preface and specified in the text. I further state that no substantial part of my dissertation has already been submitted, or, is being concurrently submitted for any such degree, diploma or other qualification at the University of Cambridge or any other University or similar institution. It does not exceed 60,000 words. Emma K Biggs ii Publications Development and characterisation of a novel glucagon like peptide-1 receptor antibody Biggs EK, Liang L, Naylor J, Madalli S, Collier R, Coghlan MP, Baker DJ, Hornigold DC, Ravn P, Reimann F, Gribble FM. Diabetologia 2018, 61 (3): 711-721. Scaling it down: new in vitro tools to get the balance right. Biggs EK, Gribble FM, Reimann F. Biochemical Journal 2017, 474 (1): 47-50. iii Table of Contents Abstract .................................................................................................................................................... i Declaration .............................................................................................................................................. ii Publications ............................................................................................................................................ iii Table of Contents ................................................................................................................................... iv Acknowledgements ................................................................................................................................ ix Abbreviations .......................................................................................................................................... x Chapter 1. Introduction .......................................................................................................................... 1 1.1 Metabolic Physiology ........................................................................................................... 1 1.1.1 Physiology of the Gastrointestinal Tract .............................................................. 1 1.1.2 Physiology of the gut-brain axis ........................................................................... 1 1.1.3 Pancreatic Physiology .......................................................................................... 2 1.1.4 Physiology of Adipose Tissue ............................................................................... 3 1.2 The Enteroendocrine System ............................................................................................... 4 1.3 Physiology of Glucagon-like peptide 1 (GLP-1) .................................................................... 6 1.3.1 Production of GLP-1 ............................................................................................. 6 1.3.2 Regulation of GLP-1 secretion ............................................................................. 7 1.3.3 GLP-1 Receptor (GLP1R) Structure and Signalling ............................................... 8 1.3.4 GLP1R Localisation ............................................................................................... 9 1.3.5 Actions of GLP-1 ................................................................................................... 9 1.3.5.1 Actions of GLP-1 in the pancreas ....................................................... 10 1.3.5.2 Extra-pancreatic actions of GLP-1 ...................................................... 11 1.3.5.3 Centrally mediated actions of GLP-1 .................................................. 12 1.4 Physiology of Glucose-dependent insulinotropic peptide (GIP) ........................................ 13 1.4.1 Production of GIP ............................................................................................... 13 1.4.2 Regulation of GIP secretion ............................................................................... 14 1.4.3 GIP receptor (GIPR) Structure and Signalling ..................................................... 14 1.4.4 GIPR Localisation ................................................................................................ 15 1.4.5 Actions of GIP ..................................................................................................... 15 1.4.5.1 Pancreatic actions of GIP ................................................................... 16 1.4.5.2 Actions of GIP in adipose tissue ......................................................... 17 1.5 Physiology of Glucagon-like peptide 2 (GLP-2) .................................................................. 18 1.5.1 Production of GLP-2 and regulation of secretion .............................................. 18 1.5.2 GLP-2 Receptor (GLP2R) Structure and Signalling ............................................. 18 1.5.3 GLP2R Localisation ............................................................................................. 18 iv 1.5.4 Actions of GLP-2 ................................................................................................. 19 1.5.4.1 Gastrointestinal actions of GLP-2 ...................................................... 20 1.5.4.2 Actions of GLP-2 outside of the gastrointestinal tract ....................... 21 1.6 Clinical Abnormalities in Metabolic Physiology ................................................................. 21 1.6.1 Therapeutic Targeting of the Gut Hormones GLP-1, GIP and GLP-2 ................. 22 1.7 Aims of Thesis .................................................................................................................... 23 Chapter 2. Generation of a GLP1R antagonistic antibody .................................................................... 24 2.1 Introduction ....................................................................................................................... 24 2.1.1 Therapeutic Targeting of GLP1R .......................................................................
Load more

Recommended publications
  • The Activation of the Glucagon-Like Peptide-1 (GLP-1) Receptor by Peptide and Non-Peptide Ligands
    The Activation of the Glucagon-Like Peptide-1 (GLP-1) Receptor by Peptide and Non-Peptide Ligands Clare Louise Wishart Submitted in accordance with the requirements for the degree of Doctor of Philosophy of Science University of Leeds School of Biomedical Sciences Faculty of Biological Sciences September 2013 I Intellectual Property and Publication Statements The candidate confirms that the work submitted is her own and that appropriate credit has been given where reference has been made to the work of others. This copy has been supplied on the understanding that it is copyright material and that no quotation from the thesis may be published without proper acknowledgement. The right of Clare Louise Wishart to be identified as Author of this work has been asserted by her in accordance with the Copyright, Designs and Patents Act 1988. © 2013 The University of Leeds and Clare Louise Wishart. II Acknowledgments Firstly I would like to offer my sincerest thanks and gratitude to my supervisor, Dr. Dan Donnelly, who has been nothing but encouraging and engaging from day one. I have thoroughly enjoyed every moment of working alongside him and learning from his guidance and wisdom. My thanks go to my academic assessor Professor Paul Milner whom I have known for several years, and during my time at the University of Leeds he has offered me invaluable advice and inspiration. Additionally I would like to thank my academic project advisor Dr. Michael Harrison for his friendship, help and advice. I would like to thank Dr. Rosalind Mann and Dr. Elsayed Nasr for welcoming me into the lab as a new PhD student and sharing their experimental techniques with me, these techniques have helped me no end in my time as a research student.
    [Show full text]
  • The Role of Clinical Proteomics, Lipidomics, and Genomics in the Diagnosis of Alzheimer's Disease
    Edith Cowan University Research Online ECU Publications Post 2013 3-31-2016 The Role of Clinical Proteomics, Lipidomics, and Genomics in the Diagnosis of Alzheimer's Disease Ian James Martins Edith Cowan University Follow this and additional works at: https://ro.ecu.edu.au/ecuworkspost2013 Part of the Medicine and Health Sciences Commons 10.3390/proteomes4020014 Martins, I. J. (2016). The Role of Clinical Proteomics, Lipidomics, and Genomics in the Diagnosis of Alzheimer’s Disease. Proteomes, 4(2), 14.Available here This Journal Article is posted at Research Online. https://ro.ecu.edu.au/ecuworkspost2013/2456 proteomes Article The Role of Clinical Proteomics, Lipidomics, and Genomics in the Diagnosis of Alzheimer’s Disease Ian James Martins School of Medical Sciences, Edith Cowan University, 270 Joondalup Drive, Joondalup 6027, Australia; [email protected]; Tel.: +61-8-6304-2574 Academic Editors: Edwin Lasonder and Jacek R. Wisniewski Received: 5 February 2016; Accepted: 28 March 2016; Published: 31 March 2016 Abstract: The early diagnosis of Alzheimer’s disease (AD) has become important to the reversal and treatment of neurodegeneration, which may be relevant to premature brain aging that is associated with chronic disease progression. Clinical proteomics allows the detection of various proteins in fluids such as the urine, plasma, and cerebrospinal fluid for the diagnosis of AD. Interest in lipidomics has accelerated with plasma testing for various lipid biomarkers that may with clinical proteomics provide a more reproducible diagnosis for early brain aging that is connected to other chronic diseases. The combination of proteomics with lipidomics may decrease the biological variability between studies and provide reproducible results that detect a community’s susceptibility to AD.
    [Show full text]
  • Cloning, Characterization, and Expression of a Human Calcitonin Receptor from an Ovarian Carcinoma Cell Line
    Cloning, characterization, and expression of a human calcitonin receptor from an ovarian carcinoma cell line. A H Gorn, … , S M Krane, S R Goldring J Clin Invest. 1992;90(5):1726-1735. https://doi.org/10.1172/JCI116046. Research Article A human ovarian small cell carcinoma line (BIN-67) expresses abundant calcitonin (CT) receptors (CTR) (143,000 per cell) that are coupled, to adenylate cyclase. The dissociation constants (Kd) for the CTRs on these BIN-67 cells is approximately 0.42 nM for salmon CT and approximately 4.6 nM for human CT. To clone a human CTR (hCTR), a BIN-67 cDNA library was screened using a cDNA probe from a porcine renal CTR (pCTR) that we recently cloned. One positive clone of 3,588 bp was identified. Transfection of this cDNA into COS cells resulted in expression of receptors with high affinity for salmon CT (Kd = approximately 0.44 nM) and for human CT (Kd = approximately 5.4 nM). The expressed hCTR was coupled to adenylate cyclase. Northern analysis with the hCTR cDNA probe indicated a single transcript of approximately 4.2 kb. The cloned cDNA encodes a putative peptide of 490 amino acids with seven potential transmembrane domains. The amino acid sequence of the hCTR is 73% identical to the pCTR, although the hCTR contains an insert of 16 amino acids between transmembrane domain I and II. The structural differences may account for observed differences in binding affinity between the porcine renal and human ovarian CTRs. The CTRs are closely related to the receptors for parathyroid hormone-parathyroid hormone-related peptide and secretin; these receptors comprise a […] Find the latest version: https://jci.me/116046/pdf Cloning, Characterization, and Expression of a Human Calcitonin Receptor from an Ovarian Carcinoma Cell Line Alan H.
    [Show full text]
  • Human Physiology Course
    Human Physiology Course Endocrine System Principles of hormonal regulation Assoc. Prof. Mária Pallayová, MD, PhD [email protected] Department of Human Physiology, PJ Safarik University FOM April 6-7, 2020 (9th week – Summer Semester 2019/2020) Chemical messenger systems Types of chemical messenger systems: Neurotransmitters Endocrine hormones Neuroendocrine hormones Paracrines Autocrines Cytokines Neurotransmitters are released by axon terminals of neurons into the synaptic junctions act locally to control nerve cell functions. Endocrine hormones are released by glands or specialized cells into the circulating blood influence the function of target cells at another location in the body. Neuroendocrine hormones are secreted by neurons into the circulating blood influence the function of target cells at another location in the body. Paracrines are secreted by cells into the extracellular fluid affect neighboring target cells of a different type. Autocrines are secreted by cells into the extracellular fluid affect the function of the same cells that produced them. Cytokines are peptides secreted by cells into the extracelular fluid can function as autocrines, paracrines, or endocrine hormones. e.g., the interleukins and other lymphokines secreted by helper cells and act on other cells of the immune system. adipokines= cytokine hormones (e.g., leptin) produced by adipocytes. Hormonal vs. Humoral ????? Hormonal vs. Humoral hormonal = endocrine humoral = endocrine + autocrine + paracrine The Endocrine Sytem the endocrine signaling communication and coordination system. relies on hormones, chemical substances that are released into the bloodstream, to deliver messages to cells of the body. Hormones and Functions Hormones are produced by: – endocrine glands – endocrine tissues (the brain, heart, kidney, adipose tissue, and GI tract).
    [Show full text]
  • International Union of Pharmacology. XXXV. the Glucagon Receptor Family
    0031-6997/03/5501-167–194$7.00 PHARMACOLOGICAL REVIEWS Vol. 55, No. 1 Copyright © 2003 by The American Society for Pharmacology and Experimental Therapeutics 30106/1047548 Pharmacol Rev 55:167–194, 2003 Printed in U.S.A International Union of Pharmacology. XXXV. The Glucagon Receptor Family KELLY E. MAYO, LAURENCE J. MILLER, DOMINIQUE BATAILLE, STEPHANE´ DALLE, BURKHARD GO¨ KE, BERNARD THORENS, AND DANIEL J. DRUCKER Department of Biochemistry, Molecular Biology and Cell Biology, Northwestern University, Evanston, Illinois (K.E.M.); Mayo Clinic and Foundation, Department of Molecular Pharmacology and Experimental Therapeutics, Rochester, Minnesota (L.J.M.); INSERM U 376, Montpellier, France (D.B., S.D.); Department of Medicine II, Grosshadern, Klinikum der Ludwig-Maximilians, University of Munich, Germany (B.G.); Institute of Pharmacology and Toxicology, University of Lausanne, Lausanne, Switzerland (B.T.); and Banting and Best Diabetes Centre, Toronto General Hospital, University of Toronto, Toronto, Ontario, Canada (D.J.D.) Abstract .............................................................................. 168 I. Introduction ........................................................................... 168 II. Secretin receptor....................................................................... 169 A. Molecular basis for receptor nomenclature ............................................ 169 B. Endogenous agonist................................................................. 169 C. Receptor structure .................................................................
    [Show full text]
  • Secretin and Autism: a Clue but Not a Cure
    SCIENCE & MEDICINE Secretin and Autism: A Clue But Not a Cure by Clarence E. Schutt, Ph.D. he world of autism has been shaken by NBC’s broadcast connections could not be found. on Dateline of a film segment documenting the effect of Tsecretin on restoring speech and sociability to autistic chil- The answer was provided nearly one hundred years ago by dren. At first blush, it seems unlikely that an intestinal hormone Bayless and Starling, who discovered that it is not nerve signals, regulating bicarbonate levels in the stomach in response to a but rather a novel substance that stimulates secretion from the good meal might influence the language centers of the brain so cells forming the intestinal mucosa. They called this substance profoundly. However, recent discoveries in neurobiology sug- “secretin.” They suggested that there could be many such cir- gest several ways of thinking about the secretin-autism connec- culating substances, or molecules, and they named them “hor- tion that could lead to the breakthroughs we dream about. mones” based on the Greek verb meaning “to excite”. As a parent with more than a decade of experience in consider- A simple analogy might help. If the body is regarded as a commu- ing a steady stream of claims of successful treatments, and as a nity of mutual service providers—the heart and muscles are the pri- scientist who believes that autism is a neurobiological disorder, I mary engines of movement, the stomach breaks down foods for have learned to temper my hopes about specific treatments by distribution, the liver detoxifies, and so on—then the need for a sys- seeing if I could construct plausible neurobiological mechanisms tem of messages conveyed by the blood becomes clear.
    [Show full text]
  • Membrane-Tethered Ligands Are Effective Probes for Exploring Class B1 G Protein-Coupled Receptor Function
    Membrane-tethered ligands are effective probes for exploring class B1 G protein-coupled receptor function Jean-Philippe Fortina, Yuantee Zhua, Charles Choib, Martin Beinborna, Michael N. Nitabachb, and Alan S. Kopina,1 aMolecular Pharmacology Research Center, Molecular Cardiology Research Institute, Tufts Medical Center, Tufts University School of Medicine, Boston, MA 02111; and bDepartment of Cellular and Molecular Physiology, Yale School of Medicine, New Haven, CT 06520 Edited by Solomon H. Snyder, Johns Hopkins University School of Medicine, Baltimore, MD, and approved March 6, 2009 (received for review January 6, 2009) Class B1 (secretin family) G protein-coupled receptors (GPCRs) peptide hormone complexes, providing important insight into modulate a wide range of physiological functions, including glu- the molecular mechanisms underlying PTH (3), corticotropin- cose homeostasis, feeding behavior, fat deposition, bone remod- releasing factor (CRF) (4), GIP (5), and exendin-4 (EXE4) (6) eling, and vascular contractility. Endogenous peptide ligands for interaction with their corresponding GPCRs. Notably, these these GPCRs are of intermediate length (27–44 aa) and include reports highlight that each of the peptides docks as an amphipathic receptor affinity (C-terminal) as well as receptor activation (N- ␣-helix in a hydrophobic groove present in the receptor ECD. terminal) domains. We have developed a technology in which a Peptide ligands that modulate class B1 GPCR function hold peptide ligand tethered to the cell membrane selectively modu- considerable promise as therapeutics. The peptidic GLP-1 mi- lates corresponding class B1 GPCR-mediated signaling. The engi- metic EXE4 (also known as exenatide or BYETTA) activates the neered cDNA constructs encode a single protein composed of (i)a GLP-1 receptor (GLP-1R) and represents the first incretin- transmembrane domain (TMD) with an intracellular C terminus, (ii) based pharmaceutical for the treatment of type 2 diabetes (7).
    [Show full text]
  • Glucagon-Like Peptide-1 Stimulates Luteinizing Hormone- Releasing Hormone Secretion in a Rodent Hypothalamic Neuronal Cell Line
    Glucagon-like peptide-1 stimulates luteinizing hormone- releasing hormone secretion in a rodent hypothalamic neuronal cell line. S A Beak, … , S R Bloom, D M Smith J Clin Invest. 1998;101(6):1334-1341. https://doi.org/10.1172/JCI610. Research Article To examine the influence of the putative satiety factor (GLP-1) on the hypothalamo-pituitary-gonadal axis, we used GT1-7 cells as a model of neuronal luteinizing hormone- releasing hormone (LHRH) release. GLP-1 caused a concentration- dependent increase in LHRH release from GT1-7 cells. Specific, saturable GLP-1 binding sites were demonstrated on these cells. The binding of [125I]GLP-1 was time-dependent and consistent with a single binding site (Kd = 0.07+/-0.016 nM; binding capacity = 160+/-11 fmol/mg protein). The specific GLP-1 receptor agonists, exendin-3 and exendin-4, also showed high affinity (Ki = 0.3+/-0.05 and 0.32+/-0.06 nM, respectively) as did the antagonist exendin-(9-39) (Ki = 0.98+/- 0.24 nM). At concentrations that increased LHRH release, GLP-1 (0.5-10 nM) also caused an increase in intracellular cAMP in GT1-7 cells (10 nM GLP-1: 7.66+/-0.4 vs. control: 0.23+/-0.02 nmol/mg protein; P < 0.001). Intracerebroventricular injection of GLP-1 at a single concentration (10 microg) produced a prompt increase in the plasma luteinizing hormone concentration in male rats (GLP-1: 1.09+/-0.11 vs. saline: 0.69+/-0.06 ng/ml; P < 0.005). GLP-1 levels in the hypothalami of 48-h-fasted male rats showed a decrease, indicating a possible association of the satiety factor with the low luteinizing hormone levels in animals with a negative energy balance.
    [Show full text]
  • Amylin: Pharmacology, Physiology, and Clinical Potential
    Zurich Open Repository and Archive University of Zurich Main Library Strickhofstrasse 39 CH-8057 Zurich www.zora.uzh.ch Year: 2015 Amylin: Pharmacology, Physiology, and Clinical Potential Hay, Debbie L ; Chen, Steve ; Lutz, Thomas A ; Parkes, David G ; Roth, Jonathan D Abstract: Amylin is a pancreatic ฀-cell hormone that produces effects in several different organ systems. Here, we review the literature in rodents and in humans on amylin research since its discovery as a hormone about 25 years ago. Amylin is a 37-amino-acid peptide that activates its specific receptors, which are multisubunit G protein-coupled receptors resulting from the coexpression of a core receptor protein with receptor activity-modifying proteins, resulting in multiple receptor subtypes. Amylin’s major role is as a glucoregulatory hormone, and it is an important regulator of energy metabolism in health and disease. Other amylin actions have also been reported, such as on the cardiovascular system or on bone. Amylin acts principally in the circumventricular organs of the central nervous system and functionally interacts with other metabolically active hormones such as cholecystokinin, leptin, and estradiol. The amylin-based peptide, pramlintide, is used clinically to treat type 1 and type 2 diabetes. Clinical studies in obesity have shown that amylin agonists could also be useful for weight loss, especially in combination with other agents. DOI: https://doi.org/10.1124/pr.115.010629 Posted at the Zurich Open Repository and Archive, University of Zurich ZORA URL: https://doi.org/10.5167/uzh-112571 Journal Article Published Version Originally published at: Hay, Debbie L; Chen, Steve; Lutz, Thomas A; Parkes, David G; Roth, Jonathan D (2015).
    [Show full text]
  • Glucose-Dependent Insulinotropic Polypeptide (GIP): from Prohormone to Actions in Endocrine Pancreas and Adipose Tissue
    PHD THESIS DANISH MEDICAL BULLETIN Glucose-dependent Insulinotropic Polypeptide (GIP): From prohormone to actions in endocrine pancreas and adipose tissue Randi Ugleholdt The two incretins, glucagon-like peptide 1 (GLP-1) and glu- This review has been accepted as a thesis with two original papers by University of cose dependent insulinotropic polypeptide (gastric inhibitory Copenhagen 14th of December 2009 and defended on 28th of January 2010 peptide, GIP) have long been recognized as important gut hor- mones, essential for normal glucose homeostasis. Plasma levels Tutor: Jens Juul Holst of GLP-1 and GIP rise within minutes of food intake and stimulate Official opponents: Jens Frederik Rehfeld, Baptist Gallwitz & Thure Krarup pancreatic β-cells to release insulin in a glucose-dependent man- ner. This entero-insular interaction is called the incretin effect and Correspondence: Department of Biomedical Sciences, Cellular and Metabolic Re- search Section, University of Copenhagen, Faculty of Health Sciences, Blegdamsvej accounts for up to 70% of the meal induced insulin release in man 3B build. 12.2, 2200 Copenhagen N, Denmark and via this incretin effect, the gut hormones facilitate the uptake of glucose in muscle, liver and adipose tissue (2). Although the E-mail: [email protected] pancreatic effects of these two gut hormones have been the target of extensive investigation both hormones also have nu- merous extrapancreatic effects. Thus, GLP-1 decreases gastric Dan Med Bull 2011;58:(12)B4368 emptying and acid secretion and affects appetite by increasing fullness and satiety thereby decreasing food intake and, if main- THE TWO ORIGINAL PAPERS ARE tained at supraphysiologic levels, eventually body weight (3).
    [Show full text]
  • The Enteral Insulin-Stimulation After Whipple's Operation
    Diabetologia 11, 207--210 (1975) by Springer-Verlag 1975 The Enteral Insulin-Stimulation after Whipple's Operation J. F. Rehfeld, F. Stadil, H. Baden and K. Fischerman Dept. of Clinical Chemistry and Surgical Gastroenterology (F), Bispebjerg Hospital; Dept. of Surgical Gastroenterology (C), Rigshospitalet; and Dept. of Surgical Gastroenterology (S), Gentofte Hospital, Hellerup, Denmark Received: January 20, 1975, and in revised form: March 17, 1975 Summary. The insulin response to oral and intravenous The results suggest, that hormones from the first part of the glucose was measured in ten patients after resection of intestinal tract are not necessary as incretins. antrum, duodenum, proximal jejunum, and the head of pan- creas (Whipple's operation). Compared to matched normal Key words: Gastrin, gastrointestinal hormones, glucose, subjects the operation reduced neither We total nor the gut incretin, insulin secretion, pancreatico-duodenectomy. hormone induced part of the insulin response to oral glucose. Oral ingestion of glucose in man causes an insulin before each test. After an overnight fast the examina- response more than twice as big as that to parenteral tion began between 8 : 00 and 9 : 00 a.m. glucose infusion [4, 6, 7]. This phenomenon has been attributed to an enteral factor called incretin [15], Experimental Procedure but the nature of incretin is still uncertain. Hormones of the upper digestive tract -- gastrin Oral Glucose Tolerance Test [2], cholecystokinin [2, 5], secretin [2], and gastric The subjects were given 50 g glucose as a 25 per inhibitory polypeptide (GIP) [3] -- have all proved cent solution flavoured with lemon. Blood samples insulinogenic in high doses.
    [Show full text]
  • Inhibition of Gastrin Release by Secretin Is Mediated by Somatostatin in Cultured Rat Antral Mucosa
    Inhibition of gastrin release by secretin is mediated by somatostatin in cultured rat antral mucosa. M M Wolfe, … , G M Reel, J E McGuigan J Clin Invest. 1983;72(5):1586-1593. https://doi.org/10.1172/JCI111117. Research Article Somatostatin-containing cells have been shown to be in close anatomic proximity to gastrin-producing cells in rat antral mucosa. The present studies were directed to examine the effect of secretin on carbachol-stimulated gastrin release and to assess the potential role of somatostatin in mediating this effect. Rat antral mucosa was cultured at 37 degrees C in Krebs-Henseleit buffer, pH 7.4, gassed with 95% O2-5% CO2. After 1 h the culture medium was decanted and mucosal gastrin and somatostatin were extracted. Carbachol (2.5 X 10(-6) M) in the culture medium increased gastrin level in the medium from 14.1 +/- 2.5 to 26.9 +/- 3.0 ng/mg tissue protein (P less than 0.02), and decreased somatostatin-like immunoreactivity in the medium from 1.91 +/- 0.28 to 0.62 +/- 0.12 ng/mg (P less than 0.01) and extracted mucosal somatostatin-like immunoreactivity from 2.60 +/- 0.30 to 1.52 +/- 0.16 ng/mg (P less than 0.001). Rat antral mucosa was then cultured in the presence of secretin to determine its effect on carbachol-stimulated gastrin release. Inclusion of secretin (10(-9)-10(-7) M) inhibited significantly carbachol-stimulated gastrin release into the medium, decreasing gastrin from 26.9 +/- 3.0 to 13.6 +/- 3.2 ng/mg (10(-9) M secretin) (P less than 0.05), to 11.9 +/- 1.7 ng/mg (10(-8) secretin) (P less than 0.02), and to 10.8 +/- 4.0 ng/mg (10(-7) M secretin) (P less than […] Find the latest version: https://jci.me/111117/pdf Inhibition of Gastrin Release by Secretin Is Mediated by Somatostatin in Cultured Rat Antral Mucosa M.
    [Show full text]